The high voltage BJT is of great interest for power conversion applications, as it is a normally-off device with very low conduction losses. One disadvantage of high voltage BJTs is a low common emitter current gain, which may include complications in building necessary gate drivers to supply the high continuous base current needed to support the BJT in its on-state. Additionally, the base layer of a BJT may have to be thicker than the maximum depletion region extension into the base in the blocking mode, to avoid a “punch-through” breakdown. This may impose limitations in the minimum thickness of the base layer and doping, and may limit the common emitter current gain.
Thus, there is a need for a BJT with improved performance characteristics, where a high common emitter current gain may be achieved without compromising blocking capability. The invention is directed to these and other important needs.